Omar Suleiman, one of Mubarak's closest associates, dies in the United States while undergoing medical tests, aid says.

CAIRO - Former Egyptian intelligence chief Omar Suleiman, one of ousted president Hosni Mubarak's closest associates, died in the United States while undergoing medical tests, a Suleiman aide and a senior security official said. He was 76.

"He was fine. It came suddenly while he was having medical tests in Cleveland," said the aide, Hussein Kamal, without giving a reason for Suleiman's death. Preparations were under way to bring Suleiman's body back home for burial, he said.

A senior Egyptian intelligence official, who did not want to be named, said he had spoken to Suleiman's son-in-law who confirmed his death.

Suleiman stepped briefly into the limelight last year when he was made Mubarak's vice president a few days before the unpopular leader was ousted in a street revolt.

The gamble failed when Egyptians massed in the streets to demand Mubarak's removal rejected the political concessions offered by Suleiman to appease the protests.

A veteran confidant of Mubarak, Suleiman had headed the Egyptian General Intelligence Services (EGIS) since 1993, taking on a prominent diplomatic role in Egypt's relations with Israel, Palestinian factions and aid donor and ally the United States.

He was quietly touted as a possible successor to Mubarak although many Egyptians believed the autocratic president would serve for life or try to hand power to his son.

After more than a year away from the public gaze, Suleiman returned to the fray this year, making a brief bid for Egypt's presidency until he was disqualified for failing to win enough signatures to take part.

He later left the country, travelling to Abu Dhabi with relatives, according to a person familiar with the matter.